Although it is less publicized than other forms of exercise, walking is one of mankind's oldest and most universal methods of muscle relaxation and stimulation. In this age of high-tech exercise equipment and low impact aerobics, many have forgotten the fact that we can achieve beneficial muscle and spinal stimulation from a simple stroll around the block.
An explanation of the dynamics of walking illustrates the various muscle and spinal movements that take place. The lower spine rests on the pelvis whereby pelvic movement controls lower spine movement. Consider the three main forces that operate on the pelvis of an upright standing person. The right and left thigh bone each push up on opposite ends of the pelvis, while the centrally located spine pushes it down. These three forces balance each other out, and the pelvis remains horizontal in the transverse direction. When a person begins to walk, weight is shifted to one foot, for example the right foot, and the left foot is lifted off the ground. At this instant, the three forces are no longer in balance. The right thigh bone pushes up on the pelvis; the spine pushes down; and the weight of the raised left leg pulls down. As a result, the pelvis tilts down on the left side and the lower spine tilts out in the direction of the left side. This spine tilt would produce a side to side motion of the upper body when walking. However, this normally does not happen because as soon as the lower spine starts its leftward tilt, the upper spine spontaneously flexes or curves itself to the right. This effectively cancels the tendency of the upper body to move to the left. A similar action occurs as the person next steps with the left foot. Thus, a stable upper body position is maintained while walking.
The above-described lateral flexing of the spine occurs during each step in the walking process and has a great effect on the health, blood circulation, and proper functioning of the organs (including digestive) located in the lower midsection. Since a normal person may take from 1000 to 10,000 steps each day, it can be seen that lateral flexing is the dominant type of repetitive movement for the spine.
In addition to the above described lateral flexing of the spine when walking, the spine also twists or rotates back and forth in a repetitive fashion. This action is necessary because of the fact that in walking first one hip and then the other will move forward of the opposite hip, yet the head instinctively remains relatively stationary. The repeated twisting of the spine compensates for the hip and pelvis rotation and thus permits the head to remain stationary and free from rotation.
The walking motions in the pelvis described above could also be described as a "wobble motion." For purposes of this disclosure, wobble motion occurs when an object tilts from side to side moving about a fixed horizontal axis, and at the same time it rotates back and forth about a fixed vertical axis. Also for purposes of this disclosure, a "wobble motion pattern" is when an object is subject to a continuing, rhythmic wobble motion. Thus, when a person is walking, the pelvis moves in a wobble motion pattern. The lower spine is closely connected to the pelvis by the sacrum which also experiences wobble motion.
Prior support devices have been proposed for providing general movement to the user. Examples of such devices include the patents to Noble, U.S. Pat. No. 4,840,425, and Morrell, U.S. Pat. No. 3,867,732. Noble discloses a seat having inflatable portions or sections 60, 62 and 64, 66 defined within the seat bottom and seat back for inflation/deflation. The Noble patent makes no distinction between the left and right sides. Morrell discloses a system similar to Noble which provides for automatic cycling. The Morrell patent also makes no distinction between the left and right sides.
Additional support devices are disclosed in the following U.S. Pat. Nos.